Histamine-producing bacteria in blue scad (Decapterus maruadsi) and their abilities to produce histamine and other biogenic amines.

Using decarboxylation medium and 16S rDNA sequence analysis, histamine-producing bacteria (HPB) in blue scad (Decapterus maruadsi) were isolated and identified, and the histamine-producing abilities of the isolated HPB were determined. Nine mesophilic strains (H1-H9) isolated from the muscle of blue scad were identified as the genera of HPB, including Arthrobacter bergeri (H1), Pseudomonas sp. (H2, H5 and H6), Psychrobacter sp. (H3), Shewanella baltica (H4 and H7), and Aeromonas salmonicida (H8 and H9), respectively. Results showed that most of the HPB strains were weak on histamine formation (13.0-20.4 mg/l), except for the H8 strain with the ability of producing 115 mg of histamine/l in trypticase soy broth containing 1.0 % L-histidine. As the strongest HPB in blue scad, bacterial strain H8 also presented a strong ability to produce other biogenic amines, such as putrescine, cadaverine, spermidine, spermine, tyramine and tryptamine. Therefore, the H8 strain identified as the genus of A. salmonicida was the dominant mesophilic HPB strain for producing histamine and other biogenic amines in blue scad at room temperature.